A year ago, an unidentified computer intruder tried to penetrate the Lower Colorado River Authority's power generation network with 4,800 high-speed log-in attempts that originated at an Internet address in China, according to a grid official's confidential memo that was leaked to the media.

And that was probably just an amateur's work, says David Bonvillain, vice president of Accuvant LABS, a cybersecurity consulting firm based in Hanover, Md.